Honestly, removing all revive tokens when time expires in matchmade grandmasters is very odd. At the very least you should keep the ones you have but be unable to make new ones, or the timers should be extended in matchmade activities by 10-20 extra minutes. Random teammates are not going to be optimal enough to clear GMs with such a strict limit and it's way too punishing to run out. Makes fireteam ops far and away the worst thing to try and farm.